High-purity dispense unit

ABSTRACT

Techniques herein include a bladder-based dispense system using an elongate bladder configured to selectively expand and contract to assist with dispense actions. This dispense system compensates for filter-lag, which often accompanies fluid filtering for microfabrication. This dispense system also provides a high-purity and high precision dispense unit. A modular hydraulic unit houses the elongate bladder and hydraulic fluid in contact with an exterior surface of the bladder. When pressurized process fluid is in the elongate bladder, hydraulic controls can selectively reduce pressure on the bladder to cause expansion, and then selectively increase hydraulic pressure to assist with a dispense action.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication No. 62/373,724, filed on Aug. 11, 2016, entitled“High-Purity Dispense Unit,” which is incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION

This disclosure relates to semiconductor fabrication, and, inparticular, to film dispensing/coating and developing processes andsystems.

Various microfabrication processes using coater/developer tools specifydifferent chemicals to be dispensed onto a substrate (wafer) forparticular designs. For example, various resist (photoresist) coatingscan be dispensed onto a substrate surface. Resist coatings can vary bytype of reaction to actinic radiation (positive/negative) and also bycomposition for different stages of patterning (front-end-of line,metallization, et cetera). Additionally, various developers and solventsmay be selected to be dispensed onto a wafer. One challenge, however, inbeing able to dispense various chemicals onto a wafer is avoidingdefects in the dispensed chemicals. Any small impurity or coagulation inthe chemical can create defects on a wafer. As semiconductor featurescontinue to decrease in size, avoiding and preventing defects fromdispensed chemicals becomes increasingly important.

SUMMARY

One option to avoid defects from liquids dispensed onto a substrate isto purchase pre-filtered chemistry for use in a coater/developer tool.Such pre-filtered chemistry, however, can be very expensive and candevelop defects in the chemistry during transport or use despitepre-filtering. Another option to avoid defects is to filter chemicals ata semiconductor fabrication tool (for example, a coater/developer“Track” tool) immediately prior to dispensing on a substrate. Onecomplication with filtering immediately prior to dispensing (point ofuse filtering) is a reduction in flow rate. For example, to deliverfluid that has been sufficiently filtered to meet purity requirements,relatively fine filters are needed. A challenge with using such finefilters is that these filters decrease a rate of fluid flow of a givenchemistry as the fluid chemistry is being pushed through theserelatively fine filters. Many semiconductor fabrication processesrequire chemistries to be dispensed at a specific flow rate (or flowrate range) that adheres to specified parameters. Having a flow rateabove or below such a given specified flow rate can result in defects ona substrate, insufficient coverage, and/or excessive coverage. In otherwords, it is difficult to push a fluid through increasingly fine filtersfast enough to meet dispense flow requirements.

Techniques disclosed herein provide a fluid delivery system thatcompensates for relatively slow fluid filtering rates whilesimultaneously providing specified dispense flow rates with digitaldispense control. In other words, systems herein can dispense a filteredliquid onto a substrate at a dispense rate faster than a filtration rateyet at high purity.

Such a system can include an apparatus for fluid delivery. A hydraulicfluid housing defines a chamber with an elongate bladder positionedtherein. The elongate bladder extends from a chamber inlet opening to achamber outlet opening. The chamber provides a bladder expansionconstraint that permits expansion of the elongate bladder to apredetermined volume and prevents expansion of the elongate bladderbeyond the predetermined volume. The elongate bladder defines a fluidflow path that is linear between the chamber inlet opening and thechamber outlet opening. The elongate bladder is configured to laterallyexpand and laterally contract within the chamber such that when theelongate bladder contains process fluid, a volume of the process fluidwithin the elongate bladder is increasable and reducible. The chamber isconfigured to contain hydraulic fluid in contact with an exteriorsurface of the elongate bladder. The hydraulic fluid housing includes adisplacement chamber in fluid connection with the chamber containing theelongate bladder. The displacement chamber includes a displacementmember that is insertable into the displacement chamber and retractablefrom the displacement chamber. The system includes a controllerconfigured to activate a volume-control system that selectivelydecreases hydraulic fluid pressure on the elongate bladder by retractinga portion of the displacement member from the displacement chambercausing expansion of the elongate bladder. The controller is configuredto activate the volume-control system that selectively increaseshydraulic fluid pressure on the elongate bladder by inserting a portionof the displacement member into the displacement chamber causingcontraction of the elongate bladder.

Such techniques can reduce defectivity of deposited films. Filmdefectivity can result from gas bubbles, fall-on particles, organicresidue/polymer, metal impurities, coagulated particles, etc. All thesedefect source and formation mechanisms are strongly impacted by acoater/developer dispense line design and configuration. One cause ormechanism for gas bubble defects can be related to gas dissolved into aliquid chemical (process fluid) to be dispensed. Dissolved gas can thenfind its way into a film during a dispense step as a bubble defect orthe bubble itself can act as a nucleation site to attract smallparticles into a big particle that is then deposited into the filmduring a dispense step. One contributing factor to particle generation,organic residue, and metal impurities is the parts that make up thedispense line (pump, valves, tanks, tubes, fittings, et cetera).

Techniques herein minimize defects that cause gas dissolution by usingan indirect dispense system. With systems herein, exposure of theprocess fluid to gas and atmosphere is minimized. Furthermore, systemsherein reduce other defect types such as fall-on particle, organicresidue/polymer and metal impurities by minimizing parts (pump, valves,tanks, tube, fitting, et cetera) that are used in a dispense lineherein. The benefit of reducing parts in the dispense line can beappreciated because every part increases a potential for causingdefects. Minimizing dead space and surface contact between process fluidand parts/hardware can minimize flow eddies by minimizing nucleationsites for chemical aggregation.

Of course, the order of discussion of the different steps as describedherein has been presented for clarity sake. In general, these steps andtechniques can be performed in any suitable order. Additionally,although each of the different features, techniques, configurations, etcetera, herein may be discussed in different places of this disclosure,it is intended that each of the concepts can be executed independentlyof each other or in combination with each other. Accordingly, thepresent invention can be embodied and viewed in many different ways.

Note that this summary section does not specify every embodiment and/orincrementally novel aspect of the present disclosure or claimedinvention. Instead, this summary only provides a preliminary discussionof different embodiments and corresponding points of novelty overconventional techniques. For additional details and/or possibleperspectives of the invention and embodiments, the reader is directed tothe Detailed Description section and corresponding figures of thepresent disclosure as further discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of various embodiments of the invention andmany of the attendant advantages thereof will become readily apparentwith reference to the following detailed description considered inconjunction with the accompanying drawings. The drawings are notnecessarily to scale, with emphasis instead being placed uponillustrating the features, principles and concepts.

FIG. 1 is a perspective view of a bladder-based dispense unit asdescribed herein.

FIG. 2 is a side view of a bladder-based dispense unit as describedherein.

FIG. 3 is a front view of a bladder-based dispense unit as describedherein.

FIG. 4 is a cross-sectional side view of a bladder-based dispense unitas described herein.

FIG. 5 is a cross-sectional side view of a bladder-based dispense unitas described herein.

FIG. 6 is a cross-sectional schematic side view of a bladder-baseddispense unit as described herein.

FIG. 7 is a cross-sectional schematic side view of a bladder-baseddispense unit as described herein.

FIG. 8 is a cross-sectional schematic side view of a bladder-baseddispense unit as described herein.

FIG. 9 is a cross-sectional schematic side view of a bladder-baseddispense unit as described herein.

FIG. 10 is a schematic diagram of a dispense system as described herein.

FIG. 11 is a cross-sectional schematic view of a nozzle and meniscussensor as described herein.

FIG. 12 is a cross-sectional schematic view of a nozzle and meniscussensor as described herein.

FIG. 13 is a cross-sectional schematic view of a nozzle and evaporationprevention device as described herein.

FIG. 14 is a cross-sectional schematic view of a nozzle and meniscuscontrol device as described herein.

FIG. 15 is a cross-sectional schematic view of a nozzle and meniscuscontrol device as described herein.

DETAILED DESCRIPTION

Techniques herein can be embodied as a bladder-based dispense systemusing an elongate bladder. This dispense system compensates forfilter-lag, which often accompanies fluid filtering formicrofabrication. This dispense system also provides a high-purity andhigh precision dispense unit. This dispense solution herein furtherreduces chances for defect creation. Conventional fluid delivery systemstypically have a “dead leg” hanging off a fluid line. This dead leg canbe a branch off the fluid line such as for a pressure measuring deviceor reservoir. Conventional fluid delivery systems can have otherdiscontinuities that result in a significant chance of creating defectsin the fluid, including various valves. Fluid connectors are designed toreduce imperfections on fluid conduit walls (inside walls). Any roughconnectors or bends can cause places where fluid can recirculate, slowdown, or otherwise get stopped which can cause coagulation. Thus, havinga piston, baffle, or side-attached reservoir to the process fluidconduit can create a lot of undesirable cross flow and create places forfluid to get stuck or slow down. Such cross flow and slow spots can leadto particle creation within the fluid. Such particles then becomedefects when dispensed on a given substrate, such as dispensingphotoresist on a silicon wafer.

Accordingly, systems herein include an elongate bladder apparatus usingin-direct pressure/volume control to dispense process fluid and minimizegas dissolution into the process fluid, and to reduce the overall partsused by a dispense system. Better fluid dispense results are achievedwhen this elongate bladder is configured to provide a cross-sectionalarea (for fluid flow) similar to that of the upstream and downstreamconduits. Such a configuration helps to prevent process fluid fromhaving cross flows or slowing of process fluid flow. As fluid enters orpasses through the elongate bladder, there is a smooth and gradualwidening to maintain laminar flow. During a dispense-off period—that iswhen fluid is not being dispensed from a corresponding nozzle onto asubstrate—process fluid can collect in this bladder (as an expandingbladder) after the process fluid is pushed through a fine filter (microfilter). In one embodiment, this elongate bladder functions as a fluidcapacitor for dispensing that is configured to be filled with processfluid having been filtered upstream or just prior to entering theelongate bladder during a dispense-off period. In some example dispenseapplications, a given fluid is dispensed at a predetermined flow rate(such as 0.4 to 1.4 cubic centimeters per second), and this fluid isdispensed (onto a substrate) for a relatively short time. For example, agiven dispense time can last for about one second and then the fluiddispense system may not be used again until after a rest period. Thisrest period may be anywhere from about 15 seconds to 60 seconds or morefor some manufacturing flows.

When dispensing from the nozzle is reinitiated, the elongate bladderunit reverses from a state of collecting process fluid to state ofexpelling process fluid. In other words, this elongate bladder has thecapacity to expand to collect a charge of process fluid and then beselectively compressed to assist with maintaining a particular processfluid flow rate by discharging the collected charge of fluid, which haspassed through a micro filter just prior to entering the elongatebladder. Thus, such a configuration provides a system having a dispensecapacitor, which includes a bladder or expandable member configured toexpand to receive a charge of fluid and to contract to help expel abuilt-up charge of fluid, all while maintaining a substantially linearflow path of the process fluid through the elongate bladder.

Expansion and contraction of the elongate bladder can be accomplishedvia a coupled hydraulic system (alternatively a pneumatic system) thatcontrols hydraulic fluid in contact with an exterior surface of theelongate bladder. There can be various cross-sectional shapes of theelongate bladder such as circular, square, and oval. For convenience indescribing embodiments herein this disclosure will primarily focus on abladder having an approximately oval or circular shape. It can bebeneficial to have tapering conical ends to connect to process fluidinput and process fluid output conduits to gradually transition from aprocess fluid conduit to a particular elongate bladder shape. Differentcross-sectional shapes offer different advantages. One advantage withusing a bladder having an oblong cross-sectional shape is having tworelatively flat opposing surfaces which can be the primary deflectionsurfaces for expansion and contraction. In cross-sectional shapes thatare substantially uniform or symmetrical (such as a circularcross-section), all sidewall surfaces would be able to expand andcontract roughly uniformly, and this shape can provide benefits too.

In typical operation, the elongate bladder has an initial shape or crosssection when there is equal pressure on the inside and outside of theelongate bladder. The elongate bladder primarily expands beyond thisinitial shape to an expanded state (some expanded state up untilreaching the bladder expansion constraint) to collect a charge ofprocess fluid and/or halt a dispense action. Then the elongate bladdercan be contracted from the expanded state to the initial state. In someembodiments the elongate bladder can be contracted to less than theinitial state for a particular dispense operation but substantialcontraction beyond the initial state is avoided to prevent defects.Indeed, the system can be configured to prevent pinching of the processfluid by the elongate bladder. If opposite inner walls contact eachother to pinch the elongate bladder, then this action could createdefects in the process fluid similar to a valve that physically andcompletely obstructs process fluid flow. The system can be configured toprevent any pinching of the process fluid by the elongate bladder. Thus,apart from the process fluid valve upstream of the process fluid filter,the system does not include any valves capable of completely obstructingprocess fluid flow through the process fluid conduit between the processfluid filter and the dispense nozzle.

In-direct pressure dispense can be executed by pulling/pushing processfluid out from a chemical bottle or process fluid source container intothe dispense system without using direct gas (gas pressure) on theprocess fluid in the source container. Such a system can use a supplybottle having an inner liner that isolates the gas that is used tosqueeze/collapse an inner bag. Alternatively, a conventionalfluid-containing bottle can be used together with a pulling device thatpulls the process fluid from the source bottle without use of a gas incontact with the process fluid. Another option is to use a gravity feedsystem incorporating a siphon mechanism.

Another aspect of embodiments herein includes a reduction of overallparts in a dispense system compared to conventional photoresist dispensesystems. Embodiments herein include many parts and valves removed fromthe dispense line (process fluid conduit) after a process fluid filter,that is, downstream the process fluid filter. Particles in the processfluid can be mostly removed with a process fluid filter, but particlescreated after the process fluid filter can result in defects on asubstrate with the defect being in a deposited film.

In some embodiments there are no moving parts in direct contact with theprocess fluid after passing the process fluid filter. That is, no movingparts apart from the bladder wall itself, but bladder wall movement isdistributed and relatively uniform, without the sharp contact or edgesassociated with conventional moving parts that create process fluiddefects. This embodiment can include having no valves after the processfluid filter. Thus, techniques herein eliminate a dispense-valve andassociated pump in that the system operates without a pump to driveprocess fluid through the system and onto a substrate.

Dispense systems herein can be divided into two areas or zones. Forexample, there is a “clean zone” area which includes a dispense systemline and components from a process fluid source to the process fluidfilter. There is also a “super clean zone” which includes the dispenseline from the process fluid filter to a dispense nozzle. The clean zonearea (upstream from process fluid filter) contains all moving parts suchas valves tanks, reservoir, etc. The super clean zone area (downstreamfrom the process fluid filter) is free of moving parts that make contactwith the process fluid (liquid).

Techniques include a dispense unit having an elongate bladder forexpansion and contraction, surrounded by hydraulic fluid, with a pistonand/or rod insertable into a hydraulic fluid for volume control of thehydraulic fluid and, by extension, for volume control of the elongatebladder. A dispense unit herein provides a high purity and highprecision dispense system. This can include electronic (digital) controlof the amount of process fluid that passes through a dispense nozzleduring a dispense operation. Also, the dispense unit can provideelectronic control of an amount of process fluid pulled back into thedispense nozzle during a post-dispense operation, which is also known assuck-back control. As part of suck-back control, the system can suckback process fluid so that a meniscus rests at a predetermined positionwithin the dispense nozzle, and then the meniscus can be held at thatposition during recharge of the bladder. Thus, techniques herein provideprecise digital suck-back control and meniscus control. Precise dispenseand suck-back is in part enabled by a precise piston and/or rod as wellas an associated motor. The precision volume-control and elongatebladder enable a valve-less system downstream from the process fluidfilter.

Techniques include a dispense nozzle with a precise fluid leveldetector. The system can detect and control a position of a meniscus ina dispense nozzle. A meniscus sensor provides continuous feedback ofliquid meniscus position in the dispense nozzle to the elongate bladderunit for continuous adjustments to bladder volume to maintain themeniscus at a desired position. Systems can include a nozzle system witha shielding device or shroud that creates a beneficial micro-environmentaround the nozzle by flowing solvent gas around the dispense nozzle toprevent drying of process fluid (such as a photoresist) in the dispensenozzle. As solvents in the process fluid evaporate (at the dispensenozzle being exposed to air because there is no valve), the evaporationcan leave behind dried particles which can easily be transferred to asubstrate in a subsequent dispense operation. Such a shielding deviceherein eliminates drying of the process fluid in the nozzle withoutusing a valve that can create defects.

Embodiments herein will now be described in more detail. Referring nowto FIGS. 1-3 a dispense unit 100 is illustrated, which can be used forfluid delivery. Such a dispense unit 100 can include a hydraulic fluidhousing 111 defining a chamber (or bladder chamber) within which anelongate bladder is positioned. Attached to the hydraulic fluid housing111 is piston rod housing 113 that contains a chamber of hydraulic fluidin fluid connection with the hydraulic fluid housing 111. Piston rodhousing 113 can be used to precisely control hydraulic fluid pressurewithin the elongate bladder unit. An actuator 114 can be employed formoving and controlling the piston rod. Bleed valve 118 can be used tofacilitate removal of air from the hydraulic system. Dispense unitsherein can be configured to operate as a self-contained hydraulicsystem—embodiments do not need hydraulic tubes or connectors extendingto the dispense unit. Embodiments can be compact and function with lowhydraulic volume.

Referring now to FIGS. 4 and 5, cross-sectional side views of an examplebladder-based dispense unit are illustrated. The elongate bladder 115extends from a chamber inlet opening 116 to a chamber outlet opening117. The chamber 119 is sized to permit expansion of the elongatebladder 115 to a predetermined volume and prevent expansion beyond thepredetermined volume. The elongate bladder defines a fluid flow paththat is linear between the chamber inlet opening 116 and the chamberoutlet opening 117. The elongate bladder is configured to laterallyexpand and contract within the chamber 119 such that when the elongatebladder contains process fluid, a volume of process fluid within theelongate bladder is increasable and reducible.

This embodiment includes a piston rod housing 113 attached to thechamber 119. The piston rod housing includes a piston 124 configuredmove within a displacement chamber. A motor, such as stepper motor 128,can be used to translate the piston 124 The displacement chamber 127 isin fluid connection with the chamber 119. Accordingly, by moving thepiston 124—when hydraulic fluid fills the chamber and displacementchamber—pressure exerted on an exterior surface of the elongate bladder115 can be increased and reduced. An anti-backlash mechanism 129 can beused to remove play from the hydraulic fluid to increase precision andcontrol of process fluid volume within the elongate bladder. Din railmount 148 can be used to secure the bladder-based dispense unit within acoater-developer tool or other dispense system that benefits fromprecisely controlled dispensing of liquid.

Thus, techniques herein can be embodied as a single cassette-stylechambered dispense unit inside a closed loop. A hydraulic displacementpin (or rod or piston or multiple pins) can impinge on the hydraulicfluid. This hydraulic fluid is in contact with exterior surface(s) ofthe elastic elongate bladder. Control for contracting the bladder is afunction of how far the pin (or piston(s) or rod(s) or plunger(s)) isinserted into the hydraulic fluid. Likewise, control for expanding thebladder is a function of how much of the pin is removed or pulled backfrom the hydraulic fluid. Accordingly, extraordinary accurate controlfor either expanding or contracting the elongate bladder is achieved.Further control of the hydraulic fluid is affected by number and sizeand combination of pins used. Having a relatively large piston that, forexample, fills an entire hydraulic fluid channel can impart relativelylarger volumetric changes. A seal can be used around the piston/rod atan opening into the hydraulic fluid chamber to prevent loss of hydraulicfluid. Using a rod or pin having a relatively small cross section canassist with incremental and small changes in volume, which can bebeneficial for dispensing relatively small amounts of fluid. Embodimentscan alternatively include using multiple rods such as having differentsize rods for affecting different volume changes.

An actuator can be used to push the piston or rod. The actuator can be astepper motor, DC motor, servo motor, or other mechanism. Selection of ahydraulic control mechanism can be based on particular dispenserequirements. For example, a given system may be designed to dispensefrom the nozzle at a rate of 0.3-1.0 mL/s. By way of a non-limitingexample, typical design considerations for dispensing photoresist onto asemiconductor wafer include dispensing fast enough to avoid drips, yetslow enough to prevent splashing onto the wafer. Dispense speed can alsobe a function of viscosity of a particular process fluid to bedispensed. Because delivery rate is a function of actuator speed,selection of a particular actuator can be based on desired dispenseparameters for a given system.

Dispense units herein can be chambered or physically constrained beyonda certain point so that the elongate bladder can be over-pressured, orover back pressured. In other words, after pressuring the bladder to acertain point (increasing bladder volume) the bladder contacts a walland no longer expands, similar to inflating a balloon in a bucket. At acertain point the elongate bladder contacts the chamber walls or abladder expansion constraint and can no longer expand. FIGS. 6 and 7 areschematic cross sectional views that illustrate this feature. In FIG. 6,elongate bladder 115 is illustrated positioned within chamber 119.Elongate bladder 115 is in a neutral expansion position and shown havinga uniform cross-section through which process fluid is flowing.Positioned around the elongate bladder 115 is bladder expansionconstraint 145. Note that hydraulic fluid 126 fills gaps between theelongate bladder 115 and the bladder expansion constraint 145. Note alsothat bladder expansion constraint 145 can include holes or gaps orperforations to provide for ingress and egress of hydraulic fluid. Thus,in one embodiment, the bladder expansion constraint 145 can beconfigured as a rigid sleeve defining a plurality of openings, or arigid mesh sleeve can be used.

As hydraulic fluid pressure exerted on the elongate bladder isdecreased, such as by retracting piston 124 from the chamber (ordisplacement chamber), fluid pressure of the process fluid can cause theelongate bladder to expand and collect a charge of fluid. This expansionis illustrated in FIG. 7. Expansion of the elongate bladder can continueuntil the bladder fully contacts the bladder expansion constraint. Atthis point the elongate bladder is prevented from expanding an internaldiameter any more. Such a physical constraint prevents hysteresis issuesfrom elastomeric material of the elongate bladder, thereby removing aneed for continuous recalibration. FIG. 8 illustrates an embodiment inwhich the chamber 119 is sized small enough to function as the bladderexpansion constraint. FIG. 8 also illustrates an embodiment that usestwo displacement members which can include a piston 124 and a rod 125.This can provide two levels of control. The piston 124 can providelarger displacement for more coarse control, while the rod 125, which issmaller, provides finer displacement control. FIG. 9 illustrates a givenembodiment in which the displacement member travels into the samechamber in which the elongate bladder 115 is positioned.

With dispense unit embodiments herein, extra hydraulic fluid is notalways needed when used with an air piston anti-backlash preload. Theair piston can avoid “spongy brakes” or slack in volume changes, so thatthe chamber does not need to have multiple pins to accurately adjustvolume. The air piston can apply pressure on the overall system to takeout any residual deformation potential or sponginess. For example, theair piston can be used to eliminate backlash in a linear actuator.Backlash herein includes lost motion when a screw changes direction andfollowing nut or ball bearing shift contact from one wall of the screwto the other. By applying constant force on the shaft, componentsmaintain contact with one side of the screw. A bleed valve for thehydraulic fluid containing area can be used to remove air within thesystem.

The system can include optical interrupting switches used as limitswitches. Alternatively, magnets at the base of rod mounts can be usedemploying either reed or Hall effect sensors. A linear encoder canoptionally be used for closed loop control or for data collection, suchas with a meniscus position sensor.

Dispense systems herein leverage the charge-accumulating and dispensingbladder to provide a valve-less dispense system after process fluidfiltration. FIG. 10 is a schematic diagram of an example dispensesystem. Process fluid is supplied or delivered from a process fluidsource 150 toward the valve 152. The process fluid source can be, forexample, a bottle of photoresist, developer, et cetera. Valve 152 is afully-closing valve and thus can start or stop flow into the greaterdispense system. From valve 152 process fluid flows toward and through afilter 154, which can be a high-purity filter to remove particles and orother contaminants. From the filter 154, process fluid flows tobladder-based dispense unit 100 that includes an elongate bladder.

The dispense unit can expand a volume of the elongate bladder to collecta charge of process fluid. When it is time to dispense process fluidonto a substrate, the dispense unit can contract the elongate bladderwhich causes filtered process fluid to flow toward the dispense nozzle137 and out the dispense nozzle to a substrate 105. Note that afterprocess fluid passes the filter 154 there are no valves in the dispenseline. This includes having no dispense nozzle valve. Accordingly,downstream of the filter 154 the system is an open-tube design.Normally, with an open-tube system, process fluid would be continuouslyflowing out of a dispense nozzle when the valve is open. But systemsherein use an expandable bladder to suck-back process fluid and collecta charge of process fluid to prevent fluid dispense at undesired times.Recharging rates can be adjusted to particular dispense cycles. Forexample, a given system may need to deposit process fluid on differentsubstrates every 30 seconds or every 45 seconds or every 60 seconds.Based on dispense cycles and process fluid filtration, a particularrecharge rate can be set. For longer periods between dispenseoperations, the valve 152 can be shut as the elongate bladder should notindefinitely collect a charge.

Having no valves after the process fluid filter means less opportunityfor defect creation. Some liquid compositions have higher tendencies toself-aggregate (such as certain silicon-containing anti-reflectivecoatings) and the self-aggregation problem increases with more physicalcontact (valves, bleed offs, etc.) and so it can be typical to purge agallon of such materials at the start of a fabrication lot or whenchanging fluids. The dispense unit and dispense system herein do notgive such materials an aggregation opportunity and thus increaseefficiency of materials use. Conventional systems typically include manymechanical elements including augmentation valves, pre-charge chambers,bleed screws, purge locations, coarse and fine needle valves, buffertanks, bubblers, et cetera, that attempt to prevent defects, but all ofthese features can themselves create defects. Accordingly, having nomechanical devices in contact with process fluid after filtration, asdisclosed herein, provides a high purity dispense, and the fine motorcontrol of the dispense unit provides high precision dispensing.

The configuration of the dispense system herein essentially separates aprocess fluid line into two areas or zones. Again referring to FIG. 10,zone 171 can be referred to as a “clean” zone, while zone 172 can bereferred to as a “super-clean” zone. Note that valve 152 as well asprocess fluid source 150 are located in the clean zone on an upstreamside of the process fluid filter. The clean zone can be considered as aless-critical area (compared to the super-clean zone) because processfluid has not yet passed through a final filter prior to dispense.Still, valve 152 can have a soft open and close as well as electroniccontrol. After the filter 154 (final filter) there are no impingement oraggregation sites, with the dispense line (conduit) being pass-throughfrom the filter 154 to the dispense nozzle 137. Thus, in the super cleanzone there are no mechanical moving parts in contact with the processfluid, save for smooth expansion and contraction of the elongatebladder.

Embodiments of the dispense system herein can also include meniscuscontrol with continuous monitoring and feedback. A meniscus sensor 138can monitor meniscus position at the dispense nozzle 137 at a relativelyhigh sample rate (ten or more cycles per second) and transmit meniscusposition data (including meniscus position changes) to a controller 142that controls the elongate bladder expansion and contraction.Accordingly a meniscus position can be maintained within a the dispensenozzle 137 at a predetermined location between dispense operations. Thisincludes control of suck-back after process fluid dispense usingexpansion of the elongate bladder.

Techniques herein can provide digital suck back in part by having enoughvolumetric shifts back and forth to keep the meniscus in play. Themeniscus can stop on a dispense line and then maintain a position withina nozzle region of the system. With conventional systems this would notbe possible using an open-tube system. Such control, however, ispossible with techniques herein leveraging the elongate bladder. Thedispense unit can be configured to respond to meniscus position feedbackwith little delay. For example a meniscus position sensor, such as anoptical sensor, identifies meniscus position and changes in meniscus(typically imperceptible to the human eye) by monitoring meniscusposition. Then a PID control loop is used to immediately make volumetricbladder changes one way or the other. For example, one response is torapidly expand the elongate bladder to uptake the volumetric change of apressure pulse that is about to hit the meniscus. A result of thisresponse is that process fluid remains in the nozzle without dispensingonto a substrate.

Any sensor can be used that can monitor a position of the meniscus in anozzle region and detect changes in position in sufficient time to relaypositional change so the dispense unit can make volumetric adjustmentsto keep the meniscus within a predetermined position range. Referringnow to FIG. 11, in one embodiment an optical sensor is used withdispense nozzle 137. An electronic light sensor 168, such as a linearphotodiode array (PDA) sensor or a charge-coupled device (CCD) sensor ispositioned on the dispense nozzle 137 or nozzle region. The nozzleregion can include the nozzle, tapered portion of a nozzle, or thenozzle and a predetermined length of conduit immediately before thedispense nozzle 137. Light source 167, such as light-emitting diodes(LEDs) are mounted opposite the light sensor to provide illumination. Anelectronic light sensor 168 can then be used to detect meniscus position169. Control loop response time can be configured to be less than tenmilliseconds. Surface mount LED's with light diffuser can alternativelybe used. Alternatively, a capacitive sensor, vision camera system,time-domain reflectometer, or ultrasonic sensor can be used. A steppermotor can be included in the control loop and can make quick changes tokeep the meniscus at a predetermined hold position. Accordingly, systemsherein can hold the meniscus at the meniscus position despite having novalve at the dispense nozzle 137 and despite any physically jarringaction to the system or variable flow rates past the process fluidfilter. Meniscus position monitoring provides digital suck back control.During a dispense operation, the elongate bladder can be contracted orcompressed using the hydraulic fluid. This action contributes to processfluid exiting the dispense nozzle onto a substrate. Additional flow canbe provided from the process fluid source. After a dispense operation iscompleted, the system can cause expansion of the elongate bladder untila meniscus of the process fluid is sucked back to a predeterminedposition within the nozzle region. Meniscus monitoring sensors can bepositioned directly on the nozzle itself, or in view of the nozzle.

Embodiments can include techniques to keep the meniscus of process fluidfrom evaporating when not dispensing to prevent defects. As has beendescribed, systems herein operate without a valve at the nozzle. At thenozzle, process fluid is maintained within the nozzle or nozzle regionwith a meniscus exposed to air. As solvents in the process fluidevaporate, the evaporation can leave behind dried particles which caneasily be transferred to a substrate in a subsequent dispense operation.Referring now to FIG. 12, embodiments can include using an evaporationshield 178, and/or a solvent gas supplier 177. The evaporation shield178 can provide a shroud, partial enclosure, or full enclosure(encapsulation) of the nozzle to prevent or reduce evaporation. A shielddevice with full enclosure can encase an end of the nozzle withouttouching the nozzle. Thus, no mechanical parts contact the meniscus forparticle generation. The evaporation shield 178 can be configured toopen and close depending on dispense actions, thereby containingevaporation when closed, and then opening to allow a dispense action.FIG. 13 illustrates an example of evaporation shield 178 in a closedposition to contain or minimize evaporation without touching the processfluid. In place of, or in addition to, the shielding device, gas-basedsolvent can be supplied to the nozzle. By saturating the air in contactwith the process fluid meniscus, solvents of the process fluid have areduced opportunity to evaporate from the process fluid to leave ahigher concentration of solids. Accordingly, such techniques can preventor reduce evaporation at the meniscus without having mechanical partsthat are in physical contact with the process fluid meniscus.

Systems herein include several operating states. One operating state isthat of holding a meniscus position. Before dispense, or during idle,the elongate bladder is used to maintain the process fluid meniscus at aspecific location within the nozzle or nozzle region using feedback froma meniscus position sensor. Another operating state is that ofdispensing fluid. If process fluid meniscus is not at a desiredposition, then the bladder is used to adjust the meniscus into position.The bladder can then dispense a desired process fluid volume at adesired rate onto a substrate, such as a semiconductor wafer, and thenstop the dispense operation, and suck-back the meniscus to a holdposition. Note that no valve is operated during the dispense operation,that is, there is no valve downstream of the process fluid filter.Another operation state is that of recharging the elongate bladder. Thevalve (on upstream side of filter) is open to allow process fluid toflow into the elongate bladder. The elongate bladder is expanded torefill a fluid charge volume as well as to manage a meniscus holdposition. When the bladder has been refilled, and no subsequent dispenseis needed, then the valve can be closed.

Systems herein can hold a meniscus position based on pixel movement.When detecting pixel movement greater than (for example) 5 pixels, thesystem can make a volume adjustment. Accordingly, with techniquesherein, a meniscus can be held at a particular hold position within +/−1millimeter of a set position. Systems herein, can be configured todispense approximately 0.5 ml in approximately one second. In oneexample recharge flow, the valve is opened to allow process fluid toflow through the filter and into the elongate bladder. Dispense unitvolume-control motor can be started using PID control to keep meniscusin hold position. Valve 152 can be closed when a stage position reachesa recharge set point. Motor can be stopped after an optional delay toallow extra fluid to bleed from the filter. Then a proportionalcontroller can be used to position the meniscus at a hold position.Depending on system parameters and sizes, recharge of filtered processfluid in the bladder can take 5-30 seconds. Thus, the system here canhave substrate cycle times of less than approximately 20 seconds.Systems herein can provide a valve-less dispense system with highrepeatability and meniscus control within approximately 1 millimeter.

Other embodiments for holding a meniscus position include configuringthe dispense nozzle and/or nozzle region to use capillary action.Capillary action can be used to create a zone having a pressuredifference without moving process fluid. In one embodiment, substantialpressure differences are created across a nozzle by using a feature inthe nozzle. For example, a sieve plate can be positioned within thenozzle just prior to the nozzle opening (or a fine filter, mesh, etcetera). By way of a non-limiting embodiment, for photoresist dispensingusing a conduit with a nozzle opening of approximately 1 mm, a platehaving a plurality of micron scale openings can be used. After processfluid passes through the sieve, process fluid can easily fall on asubstrate positioned below the nozzle. After reducing pressure to theprocess fluid, the process fluid is held on the conduit side of thesieve. There is then a threshold pressure needed to overcome thecapillary action of the sieve plate before process fluid can exit thenozzle. Accordingly, the capillary action from the sieve plate can holda meniscus of the process fluid within the nozzle region. FIG. 15illustrates an example nozzle region using sieve plate 179 to maintainmeniscus position.

Another embodiment can include using a narrowed fluid conduitimmediately prior to the dispense nozzle. As the diameter of a tubenarrows, capillary forces increase and adhesive forces between theliquid and tube can increase. Thus, with a narrowed opening immediatelyprior to exiting the dispense nozzle, fluid adhesive forces in this zonecan increase. If process fluid pressure in the process fluid conduit issufficiently reduced, then process fluid that has passed this narrowedzone shears off and exists the dispense nozzle, remaining process fluidis held within the narrowed conduit from adhesive forces. Some thresholdpressure greater than zero is then needed to restart dispensing processfluid. Otherwise, process fluid can be held within an open dispensenozzle without dripping out of the dispense nozzle. FIG. 14 illustratesan example dispense nozzle region with zone 173 having a narroweddiameter as compared to an upstream diameter to increase capillaryaction. By way of a non-limiting example, if a process fluid conduit hasa 1 mm diameter, and a dispense nozzle has a 0.8 mm diameter, then alength of the conduit immediately before the dispense nozzle can have adiameter of 0.5 mm. Such an embodiment can work with or without ameniscus sensor and with or without an evaporation prevention mechanism.

Accordingly, embodiments herein provide a fluid delivery system. Such asystem can include a hydraulic housing defining a chamber with anelongate bladder positioned within the chamber. The elongate bladderextends from a chamber inlet opening to a chamber outlet opening of thechamber. The chamber provides a bladder expansion constraint thatpermits expansion of the elongate bladder to a predetermined volume andprevents expansion of the elongate bladder beyond the predeterminedvolume. For example, a sleeve can be positioned within the chamber, orthe chamber itself can be sized to provide an expansion constraint.

The elongate bladder defines a fluid flow path that is linear betweenthe chamber inlet opening and the chamber outlet opening. The elongatebladder is configured to laterally expand and laterally contract withinthe chamber such that when the elongate bladder contains process fluid,a volume of the process fluid within the elongate bladder is increasableand reducible. In other words, as process fluid flows through a fluiddelivery line, process fluid enters a tubular bladder that substantiallymaintains laminar flow, but that can laterally expand creating a largercross-sectional area, while maintaining a tube-like shape. Variousexpansion mechanisms can be used for the elongate bladder. One mechanismis selecting the bladder from an elastomeric material that can stretchand shrink.

The chamber is configured to contain hydraulic fluid in contact with anexterior surface of the elongate bladder. The hydraulic fluid housingincludes a displacement chamber in fluid connection with the chamber.The displacement chamber includes a displacement member that isinsertable into the displacement chamber and retractable from thedisplacement chamber. The bladder chamber and the displacement chambercan optionally be a same chamber or container. Alternatively, they canbe separate chambers with one or more fluid conduits for hydraulic fluidto move back and forth.

The system includes a controller configured to activate a volume-controlsystem that selectively decreases hydraulic fluid pressure on theelongate bladder by retracting a portion of the displacement member fromthe displacement chamber causing expansion of the elongate bladder. Thecontroller is configured to activate the volume-control system thatselectively increases hydraulic fluid pressure on the elongate bladderby inserting a portion of the displacement member into the displacementchamber causing contraction of the elongate bladder.

Some embodiments can include the displacement member being a pistonhaving a diameter or cross sectional area that mostly or completelyfills an inner diameter of the displacement chamber. In other words, thedisplacement member can push or pull essentially all of hydraulic fluidin contact with a face of a piston. In other embodiments, thedisplacement member is a rod having a cross-sectional height less thanan inner height of the displacement chamber. This can be similar to apin inserted into fluid and displacing fluid by virtue of solid volumeintroduced into the chamber with hydraulic fluid in contrast to adisplacement member in contact with all interior walls of thedisplacement chamber where inserted. Both the face/end and shaft of therod is in contact with the hydraulic fluid, and so it is a volume of therod that causes displacement of hydraulic fluid. Other embodiments canuse combinations of pistons and rods which can move in unison orindependently of each other, with a piston typically causing greaterdisplacement of hydraulic fluid as compared to the rod. Yet otherembodiments can include a bellows or diaphragm pushed back and forth bythe actuator.

The chamber can be configured to enable hydraulic fluid to surround theelongate bladder. The chamber can include a rigid, elongate sleeve thatconforms to a shape of the elongate bladder. In other embodiments, thechamber walls themselves are sized to conform to the shape of thebladder. This sleeve can have multiple openings for ingress and egressof hydraulic fluid. An anti-backlash mechanism can be configured toapply pressure to the hydraulic fluid sufficient to increase a pressureresponse of the displacement member.

The volume-control system is configured to respond to input from processfluid sensors such as flow rate, meniscus position, etc. The elongatebladder is comprised of an elastomeric material. Other flexiblematerials can be used that enable expansion and contraction of theelongate bladder. For example, various plastics can be used. Theelongate bladder can have a circular, oval, or oblong cross-sectionalshape. Using an oblong cross-sectional shape can be beneficial forbetter deformability with flat surfaces. The elongate bladder has alength that is greater than a cross-sectional height. Bladdersconventionally used for industrial applications typically have a roundor square shape as a container for excess material. The bladder hereinis sized and shaped to be similar to a fluid conduit to promotecontinued laminar flow as much as possible. With a sufficiently longbladder, lateral expansion can be relatively small and still provideenough increase in volume to collect a charge of fluid, hold a meniscusposition, and dispense the collected charge of fluid.

Another embodiment includes an apparatus for fluid delivery. A hydraulicfluid housing defines a chamber having a chamber inlet opening and achamber outlet opening. An elongate bladder is positioned within thechamber and extends from the chamber inlet opening to the chamber outletopening. The elongate bladder defines a fluid flow path that is linearbetween the chamber inlet opening and the chamber outlet opening. Theelongate bladder is configured to contain process fluid within theelongate bladder separate from hydraulic fluid contained within thechamber. The elongate bladder is configured to laterally expand andlaterally contract within the chamber such that when the elongatebladder contains process fluid a volume of the process fluid within theelongate bladder is increasable and reducible. The elongate bladder canhave a length that is at least four times greater than a cross-sectionalheight of the elongate bladder.

A bladder expansion constraint is configured to permit expansion of theelongate bladder within the chamber to a predetermined volume and toprevent expansion of the elongate bladder beyond a predetermined lateralexpansion value. The bladder expansion constraint can be an elongatesleeve that is rigid that is positioned around the elongate bladder suchthat an interior surface of the elongate sleeve prevents the elongatebladder from expanding beyond an interior diameter of the sleeve. Theelongate sleeve can define one or more openings for ingress and egressof hydraulic fluid within the bladder expansion constraint.Alternatively, chamber walls or other wire mesh or other physicalconstraints can be used to constrain expansion.

The chamber is configured to maintain hydraulic fluid in contact with anexterior surface of the elongate bladder. A displacement member isinsertable into the chamber and retractable from the chamber. Thecontroller is configured to activate a volume-control system thatselectively decreases hydraulic fluid pressure on the elongate bladderby retracting a portion of the displacement member from the chambercausing expansion of the elongate bladder. The controller is alsoconfigured to activate the volume-control system that selectivelyincreases hydraulic fluid pressure on the elongate bladder by insertinga portion of the displacement member into the chamber causingcontraction of the elongate bladder.

In other embodiments, the controller is constructed and arranged toexpand the elongate bladder to a diameter greater than a diameter of thechamber inlet opening such that process fluid collects in the elongatebladder. A filter can be positioned upstream of the chamber inletopening via a fluid inlet conduit positioned to filter the process fluidat a filtration rate before the process fluid enters the elongatebladder. A dispense nozzle can be positioned downstream of the chamberoutlet opening via a fluid conduit.

Accordingly, a high-purity, high-precision dispense system is provided.

In the preceding description, specific details have been set forth, suchas a particular geometry of a processing system and descriptions ofvarious components and processes used therein. It should be understood,however, that techniques herein may be practiced in other embodimentsthat depart from these specific details, and that such details are forpurposes of explanation and not limitation. Embodiments disclosed hereinhave been described with reference to the accompanying drawings.Similarly, for purposes of explanation, specific numbers, materials, andconfigurations have been set forth in order to provide a thoroughunderstanding. Nevertheless, embodiments may be practiced without suchspecific details. Components having substantially the same functionalconstructions are denoted by like reference characters, and thus anyredundant descriptions may be omitted.

Various techniques have been described as multiple discrete operationsto assist in understanding the various embodiments. The order ofdescription should not be construed as to imply that these operationsare necessarily order dependent. Indeed, these operations need not beperformed in the order of presentation. Operations described may beperformed in a different order than the described embodiment. Variousadditional operations may be performed and/or described operations maybe omitted in additional embodiments.

“Substrate” or “target substrate” as used herein generically refers toan object being processed in accordance with the invention. Thesubstrate may include any material portion or structure of a device,particularly a semiconductor or other electronics device, and may, forexample, be a base substrate structure, such as a semiconductor wafer,reticle, or a layer on or overlying a base substrate structure such as athin film. Thus, substrate is not limited to any particular basestructure, underlying layer or overlying layer, patterned orun-patterned, but rather, is contemplated to include any such layer orbase structure, and any combination of layers and/or base structures.The description may reference particular types of substrates, but thisis for illustrative purposes only.

Those skilled in the art will also understand that there can be manyvariations made to the operations of the techniques explained abovewhile still achieving the same objectives of the invention. Suchvariations are intended to be covered by the scope of this disclosure.As such, the foregoing descriptions of embodiments of the invention arenot intended to be limiting. Rather, any limitations to embodiments ofthe invention are presented in the following claims.

The invention claimed is:
 1. An apparatus for fluid delivery, the apparatus comprising: a hydraulic fluid housing defining a chamber having an elongate bladder positioned within the chamber, the elongate bladder extending from a chamber inlet opening to a chamber outlet opening, the chamber including a bladder expansion constraint that permits expansion of the elongate bladder to a predetermined volume that is less than a volume of the chamber and prevents expansion of the elongate bladder beyond the predetermined volume, the bladder expansion constraint spanning a length of the bladder and including a plurality of perforations on walls thereof to allow flow of hydraulic fluid in and out of the bladder expansion constraint; the elongate bladder defining a fluid flow path that is linear between the chamber inlet opening and the chamber outlet opening, the elongate bladder being configured to laterally expand and laterally contract within the chamber such that when the elongate bladder contains process fluid, a volume of the process fluid within the elongate bladder is increasable and reducible; the chamber configured to contain the hydraulic fluid in contact with an exterior surface of the elongate bladder; the hydraulic fluid housing including a displacement chamber in fluid connection with the chamber, the displacement chamber including a displacement member that is insertable into the displacement chamber and retractable from the displacement chamber; and a controller configured to activate a volume-control system that selectively decreases hydraulic fluid pressure on the elongate bladder by retracting a portion of the displacement member from the displacement chamber causing expansion of the elongate bladder, the controller configured to activate the volume-control system that selectively increases hydraulic fluid pressure on the elongate bladder by inserting a portion of the displacement member into the displacement chamber causing contraction of the elongate bladder, wherein the bladder expansion constraint is an elongate sleeve that is rigid and that is positioned around the elongate bladder, and the elongate sleeve defines one or more openings for ingress and egress of hydraulic fluid within the bladder expansion constraint.
 2. The apparatus of claim 1, wherein the displacement member includes a piston having a piston diameter that fills an inner diameter of the displacement chamber.
 3. The apparatus of claim 1, wherein the displacement member is a rod having a cross sectional height that is less than half of an inner height of the displacement chamber.
 4. The apparatus of claim 3, wherein the displacement member further includes a rod and a piston, the rod and piston configured to move independently of each other, the piston causing greater displacement of the hydraulic fluid as compared to the rod.
 5. The apparatus of claim 1, further comprising an anti-backlash mechanism configured to apply pressure to an actuator to increase a pressure response of the displacement member.
 6. The apparatus of claim 1, wherein the elongate bladder is comprised of an elastomeric material. 